Abstract: Considering the fact that the diaphragm of the monitoring and pressure regulating valves is damaged frequently during the testing and operation, the RMG pressure regulating skid is carefully investigated. It turns out that most of the diaphragm damages are caused by incorrect testing and operation. This paper explains the working principle of RMG self-operated pressure regulating valve, provides the method to diagnose diaphragm damage, and discusses the causes and working conditions of the diaphragm damage during the testing and operation of the pressure regulating skid, then solutions and precautions are proposed.